The present invention relates to the area of protective sheaths, and more specifically to a sheath that covers and protects a medical device, such as a hypodermic needle, and is removable therefrom without damaging the sheathed medical device, e.g. the hypodermic needle, or injuring a clinician removing the sheath.
The use of a hypodermic needle in the medical field is well known in the art. Hypodermic needles are commonly used to deliver intravenous and intramuscular therapies, for placement of catheters, for withdrawing various body fluids, and for a multitude of other conventional procedures.
Hypodermic needles are commonly constructed from a hollow stainless steel cannula that has a proximal end connected to a standard luer taper connector and a remote distal end that is manufactured into an engineered tip or point. The manufacturers of such needles have developed sophisticated grinding techniques to generate complex tip geometries which achieve extremely sharp points. These extremely sharp points easily penetrate the skin of a patient as well as the underlying tissue(s) with only minimal discomfort to the patient and facilitate maximum control by the clinician. To reduce the drag of the hypodermic needle, during penetration with the tissue, as well as to improve comfort to the patient, manufactures will commonly treat the exterior surface of the hypodermic needle with silicone or some other lubricant.
In order to protect these rather fragile needle shafts and tips or points, as well as to protect the sterility of the hypodermic needle prior to use, a protective cap or sheath generally covers or encases the hypodermic needle. Such sheaths are commonly constructed from a plastic material such as polypropylene. The sheath surrounds, encases and encloses the hypodermic needle and is generally maintained in position by an interference fit between an inwardly facing surface of the sheath and an exterior surface of a hub supporting the hypodermic needle. Subtle variations in the needle hub and the sheaths, in addition to variations in automated assembly equipment dynamics, result in varying degrees of difficulty in removing the protective sheath from the hub to expose the hypodermic needle.
It is to be appreciated that the interference fit between the hub and the sheath must be sufficiently great to maintain engagement throughout the manufacturing, the packaging, the sterilization, and the shipping processes of the medical device. However, when a clinician desires to remove the sheath prior to use, the sheath removal force may pose a challenge to the clinician. This can translate into damaging the delicate tip or point of the hypodermic needle or possibly result in an inadvertent needle stick injury to the clinician.
The standard procedure used by clinicians for removing a sheath from a hypodermic needle is a two handed technique. That is, the clinician grabs a syringe, a catheter, or some other medical device attached to the hypodermic needle with the clinician""s dominant hand (e.g. either his or her right or left hand), then with the clinician""s non-dominant hand (e.g. either his or her left or right hand) pulls the sheath in an opposite direction to overcome the interference fit, between the sheath and the hub, and thus strip the sheath from the hypodermic needle. However, care should be taken to ensure that the sheath is removed parallel to the needle shaft, although this is rarely done. If the sheath is not removed parallel to the needle shaft, the sheath may contact and damage the fragile needle tip or point. Such contact can bend the tip creating either a burr, an indentation, a deformation, etc. (an xe2x80x9cimperfectionxe2x80x9d) in the end portion of the hypodermic needle. Such an imperfection results in a needle tip that will significantly increase the pain experienced by the patient during penetration and/or extrication of the hypodermic needle through the tissue. The imperfection can also increase the drag of the hypodermic needle when passing through the tissue, and this may, in turn, decrease the accuracy of the clinician. Finally, such imperfection in the tip may also create a puncture of the blood vessel that is more traumatic and may be more difficult to stop the bleeding following completion of the medical procedure.
Moreover, in many situations, the clinician""s non-dominant hand is occupied by one of a variety of necessary procedures, such as securing an injection sight, holding a drug vial, palpitating and/or stabilizing a vein, attending to a need of a patient, etc. In circumstances where only one hand is available for removal of the sheath, a clinician will often resort to biting the sheath with his or her teeth and pulling the hypodermic needle away from his or her mouth. Such a sheath removal procedure places the sharp needlepoint in close proximity to the clinician""s face, risking possibly injury. It also places the hypodermic needle directly in a path of the inhalation and/or exhalation breath from the mouth and/or the nose of the clinician. This increases the likelihood of microbiological contamination to the hypodermic needle, just prior to use on a patient. As with any type of exertion, an involuntary xe2x80x9cgruntxe2x80x9d or exhalation often accompanies such effort, making needle removal by the mouth extremely unsanitary and a source of contamination to the patient.
Wherefore, it is an object of the present invention to overcome the aforementioned problems and drawbacks associated with current needle sheath removal techniques and procedures currently available in the art.
The present invention generally relates to a system and a method for removing a sheath from a hypodermic needle by utilization of a one-handed technique.
The present invention also relates to a system and a method for removing a sheath from a hypodermic needle without damaging the delicate needle tip or point of the hypodermic needle while minimizing the threat of contamination to the hypodermic needle prior to use.
The present invention, in its most basic form, relates to a needle sheath with at least one arm or appendage permanently affixed to the sheath. The at least one arm or appendage is utilized to generate a mechanical force that overcomes the friction retention force between the needle hub and the sheath. This mechanical force results in an ejection force which facilitates disengagement of the sheath from the needle hub and the needle. The mechanical force is generally applied by the fingers of the hand (e.g. the index and the thumb of a clinician) holding the sheath connected to the medical device. It is to be appreciated that the medical device could be a syringe, a catheter hub, or the like. The removal system of the present invention allows for a one-handed removal of the sheath which allows the free hand of the clinician to be involved in the patient""s care or preparing a site for needle penetration, for example.
According to another embodiment of the invention, the arm or appendage incorporates a spring force that enhances the mechanical advantage required to overcome the friction retention force between the sheath and the need hub. When the interference fit is overcome by the applied force, the parts separate and the recoil of the spring propels the sheath axially along and off of the hypodermic needle. The resultant action removes the sheath in a direction that is parallel to a longitudinal axis of the hypodermic needle thereby minimizing the side forces and reducing the possibility that the sharp point will be contacted, touched or otherwise damaged during sheath removal. The hypodermic needle is then ready to be utilized on the patient via a desired medical procedure.
Another embodiment of the invention incorporates the removal means previously stated with a re-sheathing or needle protective device. This combination provides the means for safely removing the sheath using a one-handed technique, then cover or disarm the used and contaminated needle following completion of the medical procedure. Such disarming of the hypodermic needle prevents inadvertent needle sticks from a contaminated needle. It is well known that needle sticks from contaminated needles can result in diseases, such as HIV and hepatitis, being transferred to the clinician or some other care giver.